Close a race between thr_create and sysctl -w, the thr_scope_sys could

be changed when thr_create is running, and we tested it for several times.

1 files changed, 10 insertions, 7 deletions

diff --git a/sys/kern/kern_thr.c b/sys/kern/kern_thr.c
index 63b8f3c..6a5f220 100644
--- a/sys/kern/kern_thr.c
+++ b/sys/kern/kern_thr.c
@@ -76,6 +76,7 @@ thr_create(struct thread *td, struct thr_create_args *uap)
 	int error;
 	struct ksegrp *kg, *newkg;
 	struct proc *p;
+	int scope_sys;
 
 	p = td->td_proc;
 	kg = td->td_ksegrp;
@@ -87,9 +88,11 @@ thr_create(struct thread *td, struct thr_create_args *uap)
 	    (p->p_numthreads >= max_threads_per_proc)) {
 		return (EPROCLIM);
 	}
+
+	scope_sys = thr_scope_sys;
 	/* Initialize our td and new ksegrp.. */
 	newtd = thread_alloc();
-	if (thr_scope_sys)
+	if (scope_sys)
 		newkg = ksegrp_alloc();
 	else
 		newkg = kg;
@@ -99,7 +102,7 @@ thr_create(struct thread *td, struct thr_create_args *uap)
 	 */
 	id = newtd->td_tid;
 	if ((error = copyout(&id, uap->id, sizeof(long)))) {
-		if (thr_scope_sys)
+		if (scope_sys)
 			ksegrp_free(newkg);
 		thread_free(newtd);
 		return (error);
@@ -110,7 +113,7 @@ thr_create(struct thread *td, struct thr_create_args *uap)
 	bcopy(&td->td_startcopy, &newtd->td_startcopy,
 	    (unsigned) RANGEOF(struct thread, td_startcopy, td_endcopy));
 
-	if (thr_scope_sys) {
+	if (scope_sys) {
 		bzero(&newkg->kg_startzero,
 		    (unsigned)RANGEOF(struct ksegrp, kg_startzero, kg_endzero));
 		bcopy(&kg->kg_startcopy, &newkg->kg_startcopy,
@@ -124,7 +127,7 @@ thr_create(struct thread *td, struct thr_create_args *uap)
 	cpu_set_upcall(newtd, td);
 	error = set_mcontext(newtd, &ctx.uc_mcontext);
 	if (error != 0) {
-		if (thr_scope_sys)
+		if (scope_sys)
 			ksegrp_free(newkg);
 		thread_free(newtd);
 		crfree(td->td_ucred);
@@ -133,7 +136,7 @@ thr_create(struct thread *td, struct thr_create_args *uap)
 
 	/* Link the thread and kse into the ksegrp and make it runnable. */
 	PROC_LOCK(td->td_proc);
-	if (thr_scope_sys) {
+	if (scope_sys) {
 			sched_init_concurrency(newkg);
 	} else {
 		if ((td->td_proc->p_flag & P_HADTHREADS) == 0) {
@@ -145,7 +148,7 @@ thr_create(struct thread *td, struct thr_create_args *uap)
 	td->td_proc->p_flag |= P_HADTHREADS; 
 	newtd->td_sigmask = td->td_sigmask;
 	mtx_lock_spin(&sched_lock);
-	if (thr_scope_sys)
+	if (scope_sys)
 		ksegrp_link(newkg, p);
 	thread_link(newtd, newkg);
 	mtx_unlock_spin(&sched_lock);
@@ -153,7 +156,7 @@ thr_create(struct thread *td, struct thr_create_args *uap)
 
 	/* let the scheduler know about these things. */
 	mtx_lock_spin(&sched_lock);
-	if (thr_scope_sys)
+	if (scope_sys)
 		sched_fork_ksegrp(td, newkg);
 	sched_fork_thread(td, newtd);